Apparatus for sorting and shortcircuiting detonators



y 1968 SATOSHI WATANABE 3,383,753

APPARATUS FOR SORTING AND SHORT-CIRCUITING DETONATORS Filed July 21,1965 5 Sheets-Sheet 1 y 1968 SATOSHI WATANABE 3,383,753

APPARATUS FOR SORTING AND SHORT-CIRCUITING DETONATORS 5 Sheets-SheetFiled July 21, 1965 y 1968 SATOSHI WATANABE 3,383,753

APPARATUS FOR SOR'I ING AND SHORT-CIRCUITING DETONATORS Filed July 21,1965 5 sheets-sheet 5 y 1968 SATOSHl WATANABE 3,383,753

APPARATUS FOR SORTING AND SHORT-CIRCUITING DETONATORS Filed July 21,1965 5 Sheets-Sheet 4 y 21, 1 SATOSHI WATANABE 3,383,753

APPARATUS FOR SORTING AND SHORT-CIRCUITING DETONATORS Filed July 21,1965 5 Sheets-Sheet 5 3,383,753 APPARATUS FOR SORTING AND SHORT-CIRGUITING DETONATORS Satoshi Watanabe, Nobeoka-shi, Japan, assignor toAsahi Kasei Kogyo Kabushiki Kaisha, Kita-ku, Osaka, Japan, a corporationof Japan Filed July 21, 1965, Ser. No. 474,214 Claims priority,application Japan, Aug. 5, 1964, 39/44,167; Aug. 13, 1964, 39/45,422;Aug. 14, 1964, 39/45,608; Aug. 21, 1964, 39/46,412, 39/46,413

14 Claims. (Cl. 29-203) This invention relates to the manufacture ofelectric detonators and is intended to provide a novel apparatus forresistance-selecting and short-circuiting electric detonators which isdesigned to perform with safety and high production efiiciency the stepsof measuring the electric resistance of the detonator to compare themeasured resistance with a specified resistance value :for automaticselection of detonators and short-circuiting the wire terminals of theselected detonators either with metal foil or by stranding together andtwisting the wire terminals.

In the past, in the manufacture of electric detonators, the process ofselecting detonators by measurement of the resistance thereof has beenperformed manually by contacting the terminals of the lead wires withthe terminals of a resistance meter and reading the indication of thelatter or confirming a signal or the like produced. Such manualoperation has often caused improper selection, for example, due tomisreading of the meter indication. In addition, since for operatingefficiency the measuring operation has customarily been performed withmany detonators in the vicinity of the operator, some danger has alwaysbeen involved that the detonators will explode when an excessivemeasuring current is passed through the resistance meter. In addition,the operation efiiciency has been very limited as the detonators havebeen measured manually one by one.

Further, in the known process for short-circuiting electric detonatorsthe wire terminals have been manually twisted or metal foil applied tothe terminals by clamping, and variations in magnitude of the twistingor clamping force have been substantial and the magnitude itself hasgenerally been limited so that the short-circuiting has often beenelectrically incomplete, for example, because of rust formed on thesurface of the lead wires. In addition, the manud short-circuitingoperation exposes the operator to the danger of explosion just as in themeasuring operation.

The present invention is intended to provide a novel apparatus forresistance-selecting and short-circuiting electric detonators which iscapable of mechanically performing the resistance measurement, selectionand short-circuiting process included in the manufacture of electricdetonators in an automatic fashion. According to the present invention,an apparatus for resistance-selecting and short-circuiting electricdetonators comprises a turntable adapted to rotate intermittently, aplurality of detonator holders secured to said turntable at regularintervals along its periphery, and a number of station units arranged onan annular stationary base encircling said turntable, including aresistance-measuring unit, a reject discharging unit, a lead-wiregathering unit, a metal-foil supplying unit, a metal-foil pressingshort-circuiting unit, and/or a wire-twisting short-circuiting unit, anda discharging unit for discharging finished products. The turntable isrotated intermittently with electric detonators hung on the respectiveholders secured to the turntable and the station units on the stationarybase operate each time the turntable comes to rest in successive angularpositions so that the steps of measuring resistance of detonators, dis-United States Patent "ice charging faulty articles, and-short-circuiting accepted articles are automatically performed. Infurther detail, each of the electric detonators held in the respectiveholders which are secured to the intermittently rotated turntable, arefirst measured for its resistance and are automatically sorted into twogroups including acceptable and rejected articles, respectively. Therejected articles are released from the associated holders by the rejectdischarging unit and are discharged exteriorly of the machine. Theapparatus according to the present invention is constructed so that anyrejected article can never 'be sorted into the group of acceptedarticles even though the latter articles may possibly be discharged as areject. Therefore, even if some misoperation of the machine take place,faulty articles are prevented from being transferred as acceptable tothe next following station. Acceptable electric detonators thus selectedare subjected to the short-circuiting process in which the terminals ofthe detonator wires are short-circuited either with a metal foil or bytwisting together the two lead wires. For shortcircuiting the leadterminals with a metal foil, the terminals of the two lead wires arefirst brought together by the wire-gathering unit and then are wrappedwith said metal foil by the metal-foil supplying unit. Then, at the nextfoil pressing and short-circuiting station, the metal foil is firmlypressed against the two lead wires to electrically short-circuit thelatter. For short-circuit'ing by wire twisting, the terminals of the twolead wires brought together are mechanically twisted together by thewire twisting unit. The detonator thus short-circuited is delivered tothe following process by the discharging unit for discharging finishedproducts. According to a further feature of the present invention, theholders on the intermittently rotating turntable as well as the stationunits mounted on the stationary base encircling the turntable areseparated from each other by shield plates for the purpose of preventingany spread of explosion which may possibly occur during operation. Bythis means, even if any one of the detonators on the machine beexploded, there is no danger that the remaining detonators are involvedto cause serious damage.

The present invention will now be described in further detail withreference to the accompanying drawings, which illustrate one preferredembodiment of the invention and in which:

FIG. 1 is a front elevation illustrating the inventive apparatus;

FIG. 2 is a plan view of same;

FIG. 3 is a plan view of one of the holders for holding the terminals ofthe lead wires of a detonator;

FIG. 4 is a side elevation of same;

FIG. 5 is a side elevation, partly in cross section, of the rejectorunit for discharging faulty detonators;

FIG. 6 is a plan view of same;

FIG. 7 is a side elevation, partly in cross section, of thewire-gathering unit;

FIG. 8 is a front elevation of the metal-foil supplying unit;

FIG. 9 is a side elevation of same;

FIG. 10 is a side elevation of the metal-foil clamping device;

FIG. 11 is a plan view of same;

FIG. 12 is a side elevation of the metal-foil pressing andshort-circuiting unit;

FIG. 13 is a cross-sectional side elevation of the wiretwistingshort-circuiting unit;

FIG. 14 is a plan view of the discharging unit for dis charging finishedarticles;

FIG. 15 is a side elevation of same;

FIG. 16 is a plan view of an electric detonator to be sbort-ci-rcuited;

FIG. 17 is a plan view of same after it has been wrapped with a metalfoil;

FIG. 17A is a fragmentary side elevation illustrating the manner inwhich the metal foil is pressed against the lead wires to short-circuitthe latter; and

FIG. 18 is a plan view of an electric detonator shortcircuited by thewire-twisting without use of any metal foil.

Referring to the drawings and first to FIGS. 1 and 2, which illustratethe outline of the inventive apparatus for resistance-selecting andshort-circuiting electric detonators, reference numeral 1 indicates aturntable adapted to rotate intermittently by predetermined angulardistances, and reference numeral 2 indicates a plurality ofelectricdetonator holders arranged radially on the turntable 1 atregular intervals along its periphery. the holders 2 are eachconstructed so as to grip at its extremity a lead wire of an electricdetonator by way of electrical insulating means. A tubular structure 1Ais arranged beneath the turntable 1 and about the periphery thereof forthe purpose of preventing any accidental spread of explosion between thedetonators and includes partition plates corresponding in number to theholders 2. Reference numeral 3 indicates a feed station for supplyingdetonators with lead wires to the successive holders. 3A is a stationarybase encircling the turntable l and carries a number of station unitsincluding a cutter unit 4 for sizing the lead wires of detonators, aresistancerneasuring selector unit 5, a lead-wire gathering unit 7, awire-gathering unit 8, a metal-foil insrting unit 9, metal-foil pressingand short-circuiting unit 10, a shaping trimmer unit 11, a wire-twistingshort-circuiting unit 12 and a discharging unit 13 for dischargingfinished articles. Reference numeral a; indicates a reject dischargingunit provided beneath the turntable for discharging rejected articles;and reference numeral lid indicates a central stationary supporting basecarrying a lead-wire opening device 15 and a metal-foil clamping device16.

Referring next to FIGS. 3 and 4, which represent a plan and a side view,respectively, of one of the holders indicated at 2 in FIG. 2, referencenumerals i7 and 18 indicate respective clamping arms with insulationadapted to be pressed against the opposite sides of a central insulator19. These arms cooperate to grip the base terminals of the two leadwires of a detonator separately between the arm 17 and insulator 19 andbetween insulators 13 and insulator 19. Reference numeral 36 indicates acam for opening and closim the clamping arms 17 and 18.

Reference will next be made to FIGS. 5 and 6, which illustrate thestructure of the reject discharging device 6 shown in FF. 1. A supportbracket 2%) is secured to a plate 21 arranged beneath the turntable It.22 is a movable rod mounted on the bracket Ztl for vertical movement.The vertically movable rod 22 has a cam 22A at the top end in engagementwith another cam 3%) for opening and closing said holder 2 and has a lug223 in its central portion for engagement with a depressor lever 23. Acam roller 23 is secured to the another end of vertical rod 22 forcooperation with a cam 24 provided to actuate the rod 22 upwardly. Thecam 2 is designed to be rotated through a gear means in synchronism withthe rotation of the turntable 1. A coil spring 25 is arranged tonormally bias the vertical rod 22 to its upper position. A steel ball 26is arranged for keeping the vertical rod 22 in a predetermined positionand is normally biased against the rod 22 by a coil spring 27. Thedepressor lever 28 is actuated by an electromagnet 29 which isaccommodated in a casing formed of an insulating material and throughwhich the depressor lever 28 extends. The electromagnet 2? is mounted onthe plate 21 and is operable upon reception of an indication from theresistance-measuring selector unit 5 that the dctonatcr supplied isacceptable.

In FIG. 7, which illustrates the wire-gathering unit indicated at 8 inFIGURE 2 for bringing together the lead wires, reference numeral 31indicates a support frame secured to the stationary base 3A arrangedabout the turntable 1. 32 is a vertical slide rod operable to slide withcam means through guide apertures 37 and 38 provided at the top andbottom of support frame 2-1. A rotary wire-gathering tube 34 is mountedon a bracket arm 33 by way of a ball bearing incorporated therein. Thebracket arm 33 is secured to said vertical rod 32 for vertical movementtherewith. A shaft 35 has formed thereon a lug for engagement with thewire-gathering tube 3% to impart rotation thereto and the shaft 3-5carries a belt pulley 36. The wire-gathering tube 34 has at its bottom aconical recess formed with an aperture and a slit designed in conformitywith the lead wires of the electric detonator to gather the wires.

Reference will next be made to FIGS. 8 and 9, which represent a frontand a side view, respectively, of the metal-foil supplying unit shown inFIG. 2. Reference numeral 39 indicates a support bracket secured to thestationary base 3A arranged to encircle the turntable It; indicates asupply reel of metal foil for shcrt-circuiting the lead wires ofelectric detonators; 41 indicates a feed roller for feeding apredetermined length of metal foil, and the roller ll. has a slot toprevent slippage of the foil; 42 indicates a foil presser rollerarranged for contacting engagement with feed roller 41; and 43 indicatesa ratchet wheel for imparting intermittent rotation to the feed roller41 by way of gearing. A vertically movable rod 44 has a pawl 45 pivotalysecured thereto by a pin id and the rod 44 slides through the guideapertures provided at the top and bottom of the support bracket 39 torotate intermittently the ratchet wheel 43 in engagement with pawl 45. Ametal-foil inserting rod 4-8 is secured to the vertical rod 44 by way ofa mounting plate 47 for vertical movement with the rod 44. A cutterblade &9 is arranged to slide in a groove formed in the support bracket3%. A coil spring 50 is provided to bias the cutter blade &9 and aresilient plate 51 is provided to hold the blade 4Q. A ledger blade 52is arranged to cooperate with the cutter blade 4-9 to cut the metal-foilstrip 40 to a predetermined length. A vertical rod 53 is formed adjacentto one end with a rack and is guided for vertical sliding movement bythe support bracket 39. A pinion 5 meshing with the rack on the verticalrod 53, is rotatable through an angle of 90 degrees. A metal-foil gripfinger 55 is secured to a shaft 56, which carries said pinion 54, and isrotatable with the latter. The grip finger 55 is composed by a pair ofleaf springs to receive and resiliently hold the metal-foil which isV-formed.

In FIGS. 10 and 11, which illustrate the metal-foil clamping deviceindicated at 16 in FIG. 2, reference numeral 57 indicates a base framearranged on the stationary base 14 shown in FIG. 2; 58 indicates aslider base carrying a roller 72 and slidable back and forth in a grooveformed in the base frame 57 under control of a cam 59. A slider rod 60carries a wedge-formed cam 6 at its extremity and a roller 71 at theother end and slides through an aperture 58A formed in the slider base58 for back and forth sliding movement under control of a cam 61.

A spring 76 is secured at one end to the slide rod 50 by an anchor 73 tonormally urge the slide rod 60 rerawardly. A pair of clamp levers 64 and65 are pivoted at 62 and 63, respectively, to the slider base 53 andoperable upon insertion of the wedge-formed cam 66 to clamp metal-foilgrip finger 55, shown in FIG. 8. A spring 67 is provided to normaly keepthe clamp levers 64 and 65 in open position. A lead-wire presser plate68 is arranged to receive the terminals of the lead wires of a detonatorand is operable to force the terminals into the V-shaped space definedby the metal-foil as held in the metalfoil grip finger 55 when theslider base 58 is advanced. A spring 69 is provided to normally hold theslider base 58 in its retracted position.

In FIG. 12, which illustrates the metal-foil pressing short-circuitingunit indicated at in FIG. 2, reference numeral indicates a supportbracket secured to the stationary base 3A encircling the turntable 1(FIG. 2); and 81 indicates a pressure-supporting rod formed at theforward end with a groove for accommodating a ledger blade (of angularor flat form) and carries at the other end a roller to cooperate with acam 93. The pressuresupporting rod 81 is movable back and forth througha guide aperture formed in the support bracket 80 under control of cam93. A presure rod 82 is slidable back and forth through a groove formedin the top portion of the support bracket 80 under control of cam 91.Another pressure-supporting rod 83 carries at its extremity a ledgerblade 85 and is guided by an aperture formed in the support bracket forback and forth movement under control of a cam 92. A presser blade 84 isof angular or flat form and is arranged to opopse the ledger or blade85. A spring 86 is provided to adjust the force acting upon the presserblade 84 and is adjustable by a retainer nut 87. Springs 88 and 89 serveto normaly keep said pressure-supporting rods 81 and 83 in theirrespective retracted positions and a cam 94 serves to forcibly retainthe pressure-supporting rod 81 in its retracted position.

In FIG. 13, which illustrates in cross section the wiretwistingshort-circuiting unit indicated at 12 in FIG. 2, a support bracket issecured to the base 3A arranged about the turntable 1 shown in FIG. 2. Avertically movable tubular rod 101 has at its top an integraloverhanging arm formed with a circular recess, in which a ball bearing104 is arranged. The tubular rod 101 carries at its bottom a camfollower roller 102 which cooperates with a cam 103 to move the rod 101vertically through a vertical bore formed in said support bracket 100. Arotative shaft 105 carries a belt pulley 107 at its top with a frictionwheel 106 mounted at the bottom of the shaft 105 in contactingengagement with the periphery of the cam 103 on one side thereof torotate the shaft 105, which is fitted in the axial bore of the tubularrod 101. A shaft 109 is journaled in the ball bearing 104, mounted inthe overhanging arm of the tubular rod 101 and carries at the top a beltpulley 108, which is connected by a belting with pulley 107. A pair ofgrip fingers 110 and 111 are secured by leaf springs 112 and 113respectively to the bottom of the shaft 109 for the purpose of grippingthe wire terminals of a detonator. Leaf springs 112 and 113 serve tokeep the grip fingers 110 and 111 open. A ball bearing 114 is providedto close the grip fingers when they descend while rotating and thebearing 114 is fitted in a circular recess formed in a portion of thesupport bracket 100. A tension spring 115 is provided to urge thetubular rod 101 to descend and the spring normally holds the roller 102carried by the tubular rod 101 in contact with the cam 103.

Reference will next be made to FIGS. 14 and 15, which illustrate thestructure of the discharging unit 13 (FIG. 2) for discharging finishedarticles. Referrence numeral indicates a support arm secured to the base3A, which is arranged to encircle the turntable 1 as shown in FIG. 2.Seamless belts 121 and 122 are provided to carry electric detonators bygripping the lead wires of the latter and are driven by respectivepulleys 123 and 124 in the same direction. Gear wheels 132 and 133 aremounted on respective shafts 135 and 136 and a pulley 125 is arranged toimpart rotation to the gear 132 by way of pulleys 126 and 127. Pulleys128 and 129 are arranged to support the belts 121 and 122 at their endsremote from gear wheels 132 and 133. Tension rods 130 and 131 areprovided to carry the respective pulleys 128 and 129 and they are biasedby springs 137 and 138 in a direction to tension the respective belts121 and 122.

Guide plates 139 and 140 are provided to obtain a satisfactorycontacting pressure between the running belts. Idlers 134 are arrangedto guide the returning runs of the belts.

Reference will next be made to FIGS. 16, 17 and 18, in which likereferences indicate like parts. Referring first to FIG. 16, referencenumeral 141 indicates an electric detonator with lead wires 142; havingtheir naked terminals 143 which have not been short-circuited yet. InFIG. 17, a metal foil 144 is shown embracing the naked terminals 143 ofthe lead wires 142. In FIG. 17A, the metal-foil 144 is shown clampedinto corrugated form to short-circuit the lead wires. In FIG. 18,reference numeral 147 indicates the naked terminals 143 of the two leadwires 142, which are shown twisted and short-circuited to each otherwithout use of any metal-foil such as shown at 144 in FIG. 17.

The apparatus for resistance-selecting and short-circuiting electricdetonators operates as will be described hereinafter to automaticallymeasure the resistance of electric detonators for selecting acceptableones and to short-circuit the terminals of the lead wires of theselected detonators.

The operation of the apparatus will now be described in detail.

Electric detonators 141 to be short-circuited, such as shown in FIG. 16,are fed into the apparatus at the feed station 3 (FIG. 2) by theoperator to be held by the successive holders 2, secured to theturntable 1, with the naked terminal portions of the detonator wires 142held in the holders, and are carried in a circular path as the turntable1 is rotated intermittently. During this rotation, the naked terminalportions 143 of the lead wires 142 of each detonator are gripped by theclamping insulators 17 and 18 with central insulator 19 interposedbetween the terminal portions 143 for insulating the latter from eachother. The electric detonator clamped in this manner is first broughtopposite to the sizing trimmer unit 4 (FIG. 2) where the naked terminalportions 143 of the lead wires 142 are cut to size.

Subsequently, the detonator is brought opposite to the lead opening unit15, mounted on the central stationary base 14, and the naked terminalportions of the two lead wires 142 are opened by the device 15 toprevent contact between the two lead wires 142. Then, at theresistance-measuring selecting station 5, the detonators are measuredfor resistance to compare with the specified resistance value and thusonly acceptable articles are electrically selected to beshort-circuited. Faulty articles are removed by the reject dischargingunit 6 (FIG. 1). The resistance-measuring selector unit 5 is constructedto measure the detonator resistance and, only when the detonator hasproven to be acceptable does it send an electric signal to theelectromagnet 29 of the reject discharging unit 6 so that theelectromagnet 29 is actuated to force down the depressor rod 28 andhence the vertical rod 22. At this time the steel ball 26 is fitted intoa recess formed in the adjacent portion of the vertical rod 22 under thebias of spring 27 to keep the vertical rod 22 in its depressed position.Simultaneously, carn 22A mounted on top of the vertical rod 22 islowered apart from the cam 30, provided for opening and closing theholders 2 to allow the latter to proceed to the next station with theclamping arms 17 and 18 of the holder remaining in closed position. If afaulty detonator is detected, no electrical signal is transmitted fromthe resistance-measuring selector unit 5 to the electromagnet 29, andthus the electromagnet 29 of the reject discharging unit 6 remainsinoperative. Therefore, the vertical rod 22 maintains its upper positionunder the bias of spring 25 while the cam 30 for operating the holders 2is in contact with the cam 22A mounted on top of the vertical rod 22and. rotating with the turntable 1 acts to open the clamping arms 17 and18 so that the faulty article previously held in the holder 2 isreleased to fall and thus can never be forwarded to the next station. Itis noted that the spring 25, acting at all times to bias the verticalrod 22 to its upper position, not only serves in normal operation toeject any faulty article but also is effective to prevent such faultydetonator from being transferred to the next following station as anaccepted article even in the case of misoperation or any other troubleas in the measuring instrument or the electromagnet. In other words, incases where the measuring instrument or other element is inoperative,the reject discharging unit 6 operates to eject all acceptable articlesin the same manner as in its normal operation ejecting faulty ones.Therefore, with this reject discharging unit 6, any faulty article cannever be transferred to the next station through some acceptablearticles may be rejected as faulty ones.

The electric detonator selected in the manner described above issubsequently subjected to the short-circuiting process in which ametal-foil is employed or the lead wires are twisted to short-circuitthe latter. in the event that a metal-foil is used, the selecteddetonator 14]. being carried by the intermittently rotating turntable 1comes to rest immediately beneath the wire-gathering units 7 and 8 (FIG.2) and the lead wires are brought together so that a metal foil mayreadily be inserted in the next following station. in other words, theterminal portions 143 f the lead wires 142 are preliminarily broughttogether by the lead-gathering unit "7 and then carried to be positionedimmediately below th next wire-gathering unit 3. While the electricdetonator has come to rest just beneath the wire-gathering unit 8, thevertically movable rod 32 (FIG. 7) is actuated to descend and at thesame time the rotary wire-gathering tube 3a is lowered while rotatingabout its own axis. As the re alt, the terminal portions 143 of the leadwires 1 52 are collected by the conical recess formed at the bottom ofthe wire-gathering tube 34 toward '3 axis of rotation and are partlyguided into the aperture formed in the apex of the conical recess to betwisted. Subsequently, the vertical rod 32 is raised to complete thelead gathering operation. On this occasion, rotation of thewire-gathering tube 34 is caused by means of the pulley 36 mounted ontop of the shaft 35 and a keyway formed in the wire-gathering tube tocooperate with a projecting key formed in the top portion of the shaft35 and slidable in said keyway.

The electric detonator with its lead wires brought together is thenrotated until it is positioned opposite to the metal-foil supplying unit9 (FIG. 2). When the electric detonator comes to stop at this station,the vertically movable rod 44 (FIG. 9) is operated from the drivemechanism to rise. Accordingl the pawl 45 pivoted at 46 to the rod 44-drives the ratchet wheel 43 by a predetermined angular distance therebyto rotate the feed roller 41, which cooperates with the presser roller42 to draw the metalfoil strip from the supply reel 44} by apredetermined length as indicated by the arrow in FIG. 9. Vlhen thevertical rod 44 completes its foil-feeding motion in its uppermostposition, the foil cutter blade 39 (Pl 8) is subjected to the downwardbias of the resilient plate 51 and spring 59 now stressed by the rise ofthe foil inserting rod 48. Subsequently, as the vertical rod 44 startsto descend, the cutter blade 49 is lowered in advance of the descent ofthe foil inserting rod 48, which is secured to the rod 44 by way of themountin plate 47, and cooperating with the ledger blade 52 cuts themetal-toil to a predetermined length. Thereafter, the foil inserting rod48 descends to shape the metal-foil cut to length into V-form bycooperation of the T-shapcd extremity of the foil inserting rod 48 withthe rounded open slot formed in the adjacent portion of the supportbracket 3? and the rod 48 delivers the metal-foil so shaped into themetal-foil grip finger 55. immediately thereafter, the metal-foilinserting rod 42: is raised from the grip finger 55. The grip finger 55now holding the V-shaped metal-foil is tilted forwardly by an angle of90 as indicated by the arrow in FIG. 9 with rotation of the pinion 4,carried on the shaft of the grip to crnbr :c the lead terminals lid-3with the V- shaped metablfoil carried by the grip linger. On this occan, the 90 rotation of the pinion gear is produced by the correspondingrise of the vertical rod 53,

which carries a rack meshing with the pinion S ubsequently, ietablcilclamp g device 16 (PEG. 2 operated to force the lead terminals 143 intothe V-shaped metal-foil while at the same time pinching the latter toensure its en agci nt with the lead terminals To this end, the sliderbase 58 (FIGS. 20 and 11) is advanced by cam :39 into a position toclose the metal-foil gripping finger so that the lead prcsser plate 6'5forces the lead terminals 143 into the V-shaped natal-foil held in thegrip finger 55. Subsequently, the slide rod 69 is advanced beyond theadvanced p uon of the slider be e 53 to wedge the pointed extremity ofthe wedge cam so in between the clamp levers and so that the Vshapedmetal-foil is lightly clamped together with th grip linger 55. in thismanner, the lead to;

of the electric detonator are held lightly clamped with the fo. r. asshown in P16. 17. Upon completion of the above 0 orat on, the parts ofth mac stored to their normal position.

euosequ ly, the electric detonator with its lead terminals 143 clampedwith metal-foil 144 is carried further to be positioned opposite to themetal-foil pressing and short-eircaiting unit it (FIG. 2).Pressure-supporting rods 8?. and S3 (FlG. 12) extending through therespective guide apertures in the support bracket are new forced toslide therein by rotation of respective cams 92 and 93, and thuspositioned so as to r ceive the lead terminals 143 clamped withmetal-toil $1 5 in the slot formed in the forward end of the rod andaccommodating ledger olade Subsequently, the presser rod 82 mounted ontop of the support bracket 8% is advanced by rotation of cam 31 tocooperate with the ledger blade S5, carried on the extremity of thepressure supporting rod 83, so that the lead terminals 143 are pressedto gether with the metal-foil 1 54 into corrugated form as indicated at145 in FIG. 17A. On this occasion, the pressure or clamping intensitycan be freely adjusted by selecting the spring rate or" the biasingspring 86 and adjusting the retainer nut 8'7 to obtain a clamped jointsatisfactory for the electrical short-circuiting of the detonator wires.Upon completion of the clamping operation, presser rod 252 andprcssure-supporting rods and 83 are returned under control of therespective cams S and and springs 88 and Namely, first the presser rod82 is retracted under control of earn 91 and tien pressuresupporting rod31 is forced back by spring 88 and cam 94. Finally, pressure-supportingrod is retracted under the bias of spring 8 to complete the metal-foilpressing and short-circuiting operation. The retraction of the pressuresupporting rod 83 delayed behind the reiracli' of thepressure-supporting rod 81 is to facilitate the dis engagement of theclamped lead terminals from the slot in the extremity of thepressure-supporting rod 81. Now that the lead short-circuiting operationemploying metalfoil has been completed, the electric detonator istransferred to the shaping trimm r unit 11 (FIG. 2), where it is trimmedto remove any possible irregularities such as in length of the leadwires and in position of the short-circuiting foil. Finally, tiedetonator is delivered as an acceptable article to the next process bythe product discharging unit (FIG. 2).

For short-circuiting by wire tasting, the lead wires are preliminarybrought together by the wire gathering units '7 and 3 (FIG. 2) just aswith the case of the shortcircuiting operation employing metal-foil.However, in this case, the metal-foil inserting unit 9, metal-foilpressing and short-circuiting unit to and the shaping trimmer unit itare held inoperative, the 'detonator holders 2 being carried byintermittent rotation of the turntable it past these station units to befirst positioned opposite to the wire-twisting short-circuiting unit 12,where the lead terminals 43 of the detonator are twisted together to beshOrt-circuited as indicated at 1 27 in FIG. 18. That is, when thedetonator with its lead ires brought together is positioned opposite tothe wire-twisting short- 9 circuiting unit 12, the vertical tubular rod101 slidably supported in the bracket 100 (FIG. 13) is lowered under thebias of tension spring 115 with rotation of cam 103.

At the same time, the pair of grip fingers 110 and 111, provided at theoverhanging top portion of the vertical rods 101 and 113 are actuated toclose their bottom extremities toward each other because of the taperedform of the grip fingers themselves engaging the inner periphery of theinner race of the ball bearing 114 so that the lead terminals 143 of theelectric detonator positioned im mediately beneath the grip fingers aregripped between the extremities thereof now closed. At this time, theshaft 105 extending through the vertical tubular rod 101 is rotated bythe frictional engagement of the friction wheel 106, mounted on thebottom of the shaft 105 with the side of rotating cam 103. The rotationof the shaft 105 is transmitted to the shaft 109 through the medium ofthe pulley 107 on topof shaft 105, pulley 103 on top of the shaft 109and the belting interconnecting the two pulleys. By this means, the gripfingers 110 and 111 carried on the bottom of shaft 109 are rotated apredetermined number of times carrying the electric detonator with itslead terminals 143 held between the grip fingers. As a result, the leadterminals are twisted together and short-circuited as indicated at 147in FIG. 18. Upon completion of the short-circuiting operation, thetubular rod 101 is raised by the cam 103 to allow the grip fingers 110and 111 to be restored to their open position under the bias of the leafsprings 112 and 113 thereby to release the now shortcircuited leafterminals.

The electric detonator thus short-circuited with a metal-foil or by thetwisting of the lead wires is delivered to the discharging unit 13 (FIG.2) and discharged as a finished product onto an appropriate conveyor.Referring to FIG. 14, which illustrates the discharging unit, the belts1 1 and 122 are entrained about pulleys 123, 128 and 124, 129,respectively and are continuously driven so that the adjoining portionsof the two belts 121 and 122 are moved in the discharging direction. Thebelt drive includes a pair of meshing gears 132 and 133 mounted onrespective shafts 135 and 136 carrying driving pulleys 123 and 124,respectively, and pulleys 125, 126 and 127 connected by a belting with adrive shaft, pulley 125 being secured to the shaft 135. The electricdetonator being carried by one of the holders 2 mounted on the rotatingturntable 1 is brought opposite to the joining region of thecontinuously running belts 121 and 123. At this time, the holder 2 isreleased under control of the cam below and the lead terminals 143 ofthe electric detonator released from the holder 2 are inserted betweenthe adjoining portions of the belts 121 and 122 so that the detonator issuspended therefrom and delivered out for the next operation.

With the construction and arrangement described, it will be appreciatedthat the apparatus of the present invention has various advantageousfeatures as described below. First, since the resistance measurement ofelectric detonators, rejection of faulty detonators and short-circuitingof accepted detonators are all carried out mechanically in an automaticfashion, the danger previously involved in manual operation has beeneliminated. Secondly, there is no possibility in selecting detonatorsthat any faulty article he delivered to the following station as anaccepted article because of misreading of the indication or misopcrationpossibly occurring in the conventional manual procedure and the qualityof all finished products can thus be fully guaranteed. A furtheradvantage is that the short-circuiting can be effected with electricalperfection since the short-circuited joints are formed positively anduniformly by mechanical means. Particularly, it will be noted that thepresent invention is highly valuable in the industry as it hascompletely mechanized all the operations concerned, ensuring the safetyin the manufacture of electric detonators while substantially improvingthe production efficiency.

What I claim is:

1. An apparatus for handling electrical detonators to measure theirelectrical resistance, to reject detonators whose resistance values areunacceptable and to short circuit acceptable detonators, said apparatuscomprising an intermittently rotatable turntable, a plurality of holdersperipherally mounted on said turntable for releasably engagingrespective detonators, said detonators having lead wires with free ends,means for measuring the electrical resistance of the detonators in saidholders when the turntable is intermittently halted, a discharge devicefor detonators operable upon reception of a signal from the electricalresistance measuring means to release a rejected detonator from a holderwhen said signal is absent, a metal foil supplying means for severing alength of foil from a supply thereof and forming said length intoV-shape when the turntable is in rotation, said foil supplying meansfeeding a V-shaped foil to the end portions of the lead wires of said,detonator when the turntable is halted and means for securing the foilto the ends of the lead wires of a detonator by clamping the foil andthe ends of the lead wires.

2. An apparatus according to claim 1 wherein each holder is openable andclosable and includes a cam for opening and closing said holder.

3. An apparatus according to claim 2 wherein the discharging devicecomprises a vertically movable rod including a second cam at the upperend of the rod for contacting the first said cam for opening the holder,means for retaining said rod in such position that said second camcontacts said first cam, means depressing said rod to a position inwhich said second cam is out of contact with said first cam when asignal is received from the electrical resistance measuring means, meansretaining said rod at the depressed position until said holder haspassed to the next position, and means releasing said retaining means toreturn said rod to the original position before the arrival of the nextsuccessive holder.

4. An apparatus according to claim 3 wherein the means depressing thevertically movable rod comprises a lever for depressing the rod, and anelectromagnet for operating said lever, said electromagnet being adaptedfor receiving signals from the resistance measuring means and operableonly when an acceptable detonator is detected.

5. An apparatus according to claim 1 wherein the means of supplying themetal foil comprises a metal foil holding means turnable by degrees tosupply the V-shaped metal foil to the ends of the lead wire of thedetonator, means for feeding a metal foil of constant length when saidturntable is rotating, a first vertical movable rod having means forsevering said metal foil and depositing the severed foil into saidholding means to form said severed foil into a V-shape, and a secondvertically movable rod turning said holding means by an angle of 90degree in the upward movement thereof and returning said holding meansto replace to the original position in the downward movement thereofwhen the turn-table is halted.

6. An apparatus according to claim 5 wherein said metal foil holdingmeans include two spring plates.

7. An apparatus according to claim 5 wherein said means for feeding themetal foil comprises two rolls rotatable in contact with each other andbetween which the metal foil is clamped and means for driving said rollsin rotation.

8. An apparatus according to claim 5 wherein the first rod includes apawl, a gear being provided for driving the foil feeding means, saidpawl engaging said gear in the upward stroke of said first rod androtating said gear by a constant angle, the first rod further includinga depressing rod with a cutting edge constituting the means for severingthe foil and depositing the same into the holding means.

9. An apparatus according to claim 5 wherein the sec- 0nd rod isprovided with a linear tooth for engaging with a gear driving theholding means.

10. An apparatus according to claim 1 wherein the means for securing themetal foil piece to the lead wires of the detonator comprises a slidingbase having clamping arms on the end thereof and a sliding rod having awedgeshaped cam on the end of said sliding base.

11. An apparatus according to claim 10 comprising cam means forforwardly driving the sliding base and the sliding rod when theturntable is halted.

12. An apparatus according to claim 1 wherein the means for securing themetal foil to the lead wires of the detonator comprises a first slidingrod having a guide groove on the end thereof, a second sliding rodhaving a References Cited UNITED STATES PATENTS 2,417,488 3/1947Handforth 20981 2,515,780 7/1950 Lcfren 861 3,244,103 4/1966 Spickard102-28 M. HENSON WOOD, 111., Primary Examiner.

R. A. SCHACHER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,383,753 May 21, 1968 Satoshi Watanabe It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

In the heading to the printed specification, line 8, "Aug. 5 1964"should read Aug. 6, 1964 Signed and sealed this 16th day of December1969.

I Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

1. AN APPARATUS FOR HANDLING ELECTRICAL DETONATORS TO MEASURE THEIRELECTRICAL RESISTANCE, TO REJECT DETONATORS WHOSE RESISTANCE VALUES AREUNACCEPTABLE AND TO SHORT CIRCUIT ACCEPTABLE DETONATORS, SAID APPARATUSCOMPRISING AN INTERMITTENTLY ROTATABLE TURNTABLE, A PLURALITY OF HOLDERSPERIPHERALLY MOUNTED ON SAID TURNTABLE FOR RELEASABLY ENGAGINGRESPECTIVE DETONATORS, SAID DETONATORS HAVING LEAD WIRE WITH FREE ENDS,MEANS FOR MEASURING THE ELECTRICAL RESISTANCE OF THE DETONATORS IN SAIDHOLDERS WHEN THE TURNTABLE IS INTERMITTENTLY HALTED, A DISCHARGE DEVICEFOR DETONATORS OPERABLE UPON RECEPTION OF A SIGNAL FROM THE ELECTRICALRESISTANCE MEASURING MEANS TO RE-